Blue-green laser diodes

Semiconductor laser diodes (LDs) have been playing a central role in many systems, such as high transmission-rate communication systems, high power energy source systems, and optical or magneto-optical memory systems, e.g.,consumer audio Compact Disc (CD) ROM systems, Mini-Disc (MD) ROM/RAM systems with AlGaAs infra-red LDs, and high definition MUSE disk systems with AlGaInP red-emitting LDs. The research and development, or the evolution, of the semiconductor LDs will be twofold. One is to integrate the conventional LDs, which have already been established as a discrete chip, into monolithic highly-functional devices. The AlGaAs/GaAs-based LDs have been in this phase. The other is to establish a discrete chip that achieves challenging targets, such as a super high power, an extremely rapid response, and a short wavelength. As the next generation of conventional LDs, the short wavelength, green and blue, LDs have been needed for higher density disk systems. It is straight forward that the shorter the wavelength becomes, the higher the density of those optical disks can be, leading to either a long time or a high definition recording. Furthermore, with the green and the blue LDs we are entering a new paradigm where RGB full-color all-solid-state light-sources are at hand in an inexpensive, mass productive, and highly compact manner.